Abstract
Background: Nitric Oxide (NO) has a role in immunitary defense, regulation of mucosal blood flow and mucus production, regulation of smooth muscle contraction, cerebral blood flow, glucose regulation, and mitochondrial function. NO can be synthetized endogenously through the L-arginine-NO pathway or it can be absorbed by the human intestine through the dietary intake. Most of the ingested NO is in the form of nitrate (). is a substrate of oral and intestinal microbiota and, at the end of the catabolic pathway, NO is released. Using antibacterial mouthwashes leads to an alteration of salivary metabolism, however, with unclear consequences on the circulating NO levels. The aim of this study is to perform a systematic review in order to elucidate if the alterations of oral microbiota lead to modifications in plasma NO content.Methods: Electronic databases were screened, using the following terms: [“oral bacteria” and (nitrate OR nitrite OR nitric)]. Clinical studies reporting and measurements in blood and their correlation to oral microbiota variations were included. We focused on the correlation between the changes in oral microbiota and plasma concentrations of nitrites (primary outcome). Subsequently, we investigated if modifications in oral microbiota could lead to changes in blood pressure and salivary concentration (secondary outcome).Results: Six studies, for a total of 82 participants were included in this review. In four studies, the use of mouthwash correlated to a reduction of plasma nitrite concentration (p < 0.05); Two studies did not find any difference in plasma nitrate or nitrite concentration. In five studies, a correlation between blood pressure (BP) changes and antibacterial mouthwashing emerged. Anyway, only three studies suggested a significant increase of systolic BP following mouthwashing compared with controls.Conclusions: Although, the role of oral bacteria has been unequivocally demonstrated in the regulation of salivary metabolism, their influence on plasma concentration of NO species remains ambiguous. Further studies with larger sample size are required in order to demonstrate if an alteration in oral microbiota composition may influence the blood content of //NO and all the linked biological processes.
Highlights
The specific contributions of oral microbiota in human physiopathology has not been explored yet, different studies report how the composition of oral microbiota has a role in oral and systemic diseases (Santarelli et al, 2015; Sampaio-Maia et al, 2016; Aarabi et al, 2018; Cardoso et al, 2018).In particular, some resident bacteria in the oral cavity are able to reduce (NO−2 ).the dietary intake of nitrates (NO−3 ), producing nitrites Among these, Neisseria, Veillonella, Haemophilus, Porphyromonas, Fusobacterium, Prevotella, Leptotrichia, Brevibacillus, and Granulicatella are mainly involved in this process (Doel et al, 2005; Hyde et al, 2014)
Nitrate is absorbed in the gastrointestinal tract and enters in the bloodstream. It mixes to the endogenous nitrate, which mainly derives from the L-arginine-nitric oxide (NO) pathway (Leaf et al, 1989)
Salivary nitrate is metabolized to nitrite by oral commensal bacteria and it can be further reduced to nitric oxide (NO)
Summary
The specific contributions of oral microbiota in human physiopathology has not been explored yet, different studies report how the composition of oral microbiota has a role in oral and systemic diseases (Santarelli et al, 2015; Sampaio-Maia et al, 2016; Aarabi et al, 2018; Cardoso et al, 2018).In particular, some resident bacteria in the oral cavity are able to reduce (NO−2 ).the dietary intake of nitrates (NO−3 ), producing nitrites Among these, Neisseria, Veillonella, Haemophilus, Porphyromonas, Fusobacterium, Prevotella, Leptotrichia, Brevibacillus, and Granulicatella are mainly involved in this process (Doel et al, 2005; Hyde et al, 2014). Nitrate is absorbed in the gastrointestinal tract and enters in the bloodstream It mixes to the endogenous nitrate, which mainly derives from the L-arginine-NO pathway (Leaf et al, 1989). Salivary nitrate is metabolized to nitrite by oral commensal bacteria and it can be further reduced to nitric oxide (NO). NO may contribute to a myriad of biological processes, among which: immunitary defense, regulation of mucosal blood flow and mucus production, regulation of smooth muscle contraction, cerebral blood flow, glucose regulation, and mitochondrial function (Bryan and Loscalzo, 2011). Nitric Oxide (NO) has a role in immunitary defense, regulation of mucosal blood flow and mucus production, regulation of smooth muscle contraction, cerebral blood flow, glucose regulation, and mitochondrial function. The aim of this study is to perform a systematic review in order to elucidate if the alterations of oral microbiota lead to modifications in plasma NO content
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